Bioequivalence of three brands of ciprofloxacin marketed in Lagos, Nigeria

Abstract

Background: When two formulations of the same drug are equivalent in the rate and extent to which the active drug ingredient is absorbed and becomes equally available at the site of drug action, they are bioequivalent and could be said to be therapeutically active.

Objective: The study investigated the bioequivalence of two brands of ciprofloxacin tablets with a reference product using urinary excretion

Methods: The study design was an open, single dose, randomized, three-treatment, three-period crossover design with two 14-days washout period. Each participant was given a single dose of 500 mg Ciprofloxacin with 250 mL of table water. Urine samples were collected for a period of 36 hours. The amount of ciprofloxacin excreted unchanged was evaluated by a validated ultraviolet spectrophotometric method.

Results: The parametric estimates for urinary excretion data obtained were compared. The elimination rate constants (K) were estimated as 0.11 -1 ± 0.03, 0.12 ± 0.03 and 0.13 ± 0.04 h ; the excretion rate constants (k ) were evaluated as 0.21 ± 0.12, e-1 0.25 ± 0.11 and 0.22 ± 0.10 mgh whilst elimination half-lives (t ) were estimated as 6.3 ± 1.2, 5.8 ± 0.5 1/2and 5.3 ± 0.3 h for generic products A, B and reference respectively. The mean cumulative amount of drug excreted unchanged was used asbioequivalence determinant. The confidence intervals, CI (90 %) for the cumulative amount of ciprofloxacin excreted unchanged were determined by evaluating log-transformed generic products A & B/reference ratio. The 90 % CI obtained for generic product A and B were 101.8 – 110.8 and 98.2- 106.1 % respectively.

Conclusion: It can be concluded that the 90 % CI for the bioequivalence determinant was within the bioequivalence acceptable limit of 80 – 125 %.  Therefore the two generic products could be said to be therapeutically equivalent.